French oil giant Total has hired Houston-based Wild Well Control to stop a natural gas leak at Total's Elgin platform in the North Sea.

Total spokesman Frederic Texier said Wild Well Control will conduct an operation called a top kill in an effort to plug a natural gas well about 150 miles from Aberdeen, Scotland, that is leaking 7 million cubic feet a day of highly explosive natural gas.

Total discovered the gas leak on March 25 and evacuated its staff. The well is in 1,700 feet of water, but the leak itself is from equipment on the surface.

The top kill involves pumping a mudlike substance into the well to push the gas back toward the reservoir, then capping the well.

Wild Well Control, a 36-year-old emergency well response company, developed a subsea well containment system that includes flying equipment and personnel to oil spills worldwide after BP's Macondo well blew out in the Gulf of Mexico in 2010. Wild Well Control participated in the effort to control that well, including firefighting, oil dispersal and well containment.

Wild Well's work will need approval from Britain's Health and Safety Executive, an independent regulator that oversees work-related health and safety issues.

"We are talking with the HSE and waiting for good weather conditions," Texier said. "We hope to send a helicopter out to the platform on Wednesday or Thursday."

Total also plans to drill relief wells to intercept the leaking one and has two drilling rigs in the area for that operation. It has vessels ready to carry out underwater inspections and seabed surveys of possible locations for relief wells.

It estimates its initial response is costing $1 million per day, which will increase to $1.5 million per day when drilling begins on the relief wells.

Completing them could take as long as six months, Texier said.

"The top kill will take days or weeks," he said, "and drilling the relief wells will take months."

The leak began as workers were capping and abandoning the well for production later. Total says it hasn't determined the cause of the leak.

The facility had been considered too dangerous to board until last weekend, when a flare the company feared could ignite natural gas condensate burned out.